About Omphalotus olivascens H.E.Bigelow, O.K.Mill. & Thiers
Omphalotus olivascens, commonly called the jack o'lantern mushroom, has the following physical characteristics. Its cap measures 4–18 cm (1.6–7.1 in) wide, while its stalks are 4–15 cm (1.6–5.9 in) long and 1–4 cm (0.39–1.57 in) wide. Its spores range in color from white to pale yellow. This mushroom is endemic to the west coast of North America, specifically within the California Floristic Province. It grows as either a saprobe or parasite, and is most often found growing on oak or Eucalyptus trees, only rarely occurring on other host types. Like other species in the Omphalotus genus, it causes white rot in tree hosts by breaking down the tree's lignin. The jack o'lantern mushroom is poisonous. While consumption of it is not lethal, it causes very severe cramps, vomiting, and diarrhea. Many Omphalotus species contain the toxic sesquiterpene compound illudin S; illudin S and illudin M have both been identified in Omphalotus nidiformis. Both of these illudins are common across the Omphalotus genus, and are not found in any other basidiomycete mushrooms.
